Light emitting diodes (LEDs) are semiconductor devices that convert electricity into ultraviolet rays, infrared rays, or visible light using characteristics of compound semiconductors. The LEDs are being used for home appliances, remote controllers, large-scale screen, etc.
LED light sources having high brightness are being used for lighting lamps. In addition, since such an LED light source has high energy efficiency, low replacement cost due to a long life cycle, and durability against vibration or shock and does not use toxic substances such as mercury, existing incandescent lamps or fluorescent lamps are being replaced with LED light sources of energy-saving, environmental protection and reducing costs.
Also, LEDs are favorable for light sources of middle or large sized LCD televisions and monitors. The LEDs have superior color purity and low power consumption and allow easy miniaturization when compared to cold cathode fluorescent lamps (CCFLs) mainly used for light sources of the current liquid crystal displays (LCDs). Thus, the prototypes of these LEDs are being mass-produced, and also, researches with respect to the LEDs are being more actively conducted.
In recent, various technologies, which use a blue LED and realize white light using a quantum dot (QD) emitting red light and green light as a phosphor are being developed. This is done because the white light realized using the quantum dot has high brightness and superior color reproductivity.
Nevertheless, the need of researches for reducing light losses, which may occur in case where the LED is applied to LED backlight units, and improving color uniformity is on the rise as ever.